[vlc] Problems taking MPEG4 multicast snapshots

[David Irwin]

All,

 

I posted this in the VideoLAN forums without any response. I'm trying to
use VLC as part of a video snapshot tool but am experiencing problems with
VLC snapshots. In particular, I'm experiencing problems when trying to
take a snapshot of MPEG4 multicast video from an Optelecom hardware
encoder. I use an SDP file to define each video stream/connection
information. The problem is that VLC will occasionally save the wrong
snapshot image to a file.

 


For example, here's a typical setup that I use via telnet before starting
any snapshots:

new cam172_30_28_33 broadcast loop enabled
setup cam172_30_28_33 input etc/camera_configs/cam172_30_28_33.sdp
setup cam172_30_28_33 option vout=image
setup cam172_30_28_33 option image-out-format=jpeg
setup cam172_30_28_33 option
image-out-prefix=/home/vlc/snapshots/cam172_30_28_33
setup cam172_30_28_33 option image-out-ratio=150
setup cam172_30_28_33 option image-out-replace

new cam172_30_28_36 broadcast loop enabled
setup cam172_30_28_36 input etc/camera_configs/cam172_30_28_36.sdp
setup cam172_30_28_36 option vout=image
setup cam172_30_28_36 option image-out-format=jpeg
setup cam172_30_28_36 option
image-out-prefix=/home/vlc/snapshots/cam172_30_28_36
setup cam172_30_28_36 option image-out-ratio=150
setup cam172_30_28_36 option image-out-replace



I then have a loop in my application, that communicates to VLC via telnet,
that starts one camera, then stops it, then starts the other, stops the
other, and continues in this loop forever. VLC will occasionally save the
snapshot from the 172.30.28.33 encoder as cam172_30_28_36.jpeg. I've read
through the SDP specification so that should be correct. 

My application (written in Java) runs on Debian and connects to VLC
0.8.6a. 

Anyone else have similar experiences or suggestions?

Thanks,

 

Dave Irwin


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